Dry sausage casing

ABSTRACT

A synthetic tubular sausage casing for processing dry sausages is prepared by impregnating or coating a reinforcing paper, preferably a saturating tissue, with a solution or dispersion of a water-soluble or dispersible protein, having a molecular weight above about 10,000 and an isoelectric point in the range from pH 2 to pH 6. The solution or dispersion is of a concentration such that the protein is impregnated in or coated on the paper at a concentration of about 0.1 percent -6.0 percent based on dry weight of the paper. The paper coated or impregnated with protein is cross linked by reaction with a nontoxic cross-linking agent (nontoxic in the resulting product). The coated or impregnated paper is then formed into a tubular casing and impregnated with viscose or other suitable material which is hardened or regenerated in and upon the protein saturated or coated paper reinforcement.

United States Patent OBrien et all.

[ Feb. 29, 1972 22 VISOQSE WASHING Primary Examiner-Frank W. LutterAssistant Examiner-Robert Halper Attorney-Neal J. Mosely and David V.Munnis [57} ABSTRACT A synthetic tubular sausage casing for processingdry sausages is prepared by impregnating or coating a reinforcing paper,preferably a saturating tissue, with a solution or dispersion of awater-soluble or dispersible protein, having a molecular weight aboveabout 10,000 and an isoelectric point in the range from pH 2 to pH 6.The solution or dispersion is of a concentration such that the proteinis impregnated in or coated on the paper at a concentration of about 0.1percent -6.0 percent based on dry weight of the paper. The paper coatedor impregnated with protein is cross linked by reaction with a nontoxiccross-linking agent (nontoxic in the resulting product). The coated orimpregnated paper is then formed intoa tubular casing and impregnatedwith viscose or other suitable material which is hardened or regeneratedin and upon the protein saturated or coated paper reinforcement.

9 Claims, 5 Drawing Figures PRODUCT REELING AND STORAGE DRY SAUSAGECASING BACKGROUND OF THE INVENTION l Field of the Invention Dry sausage,of which the various salami and cervelats are prime examples, isconventionally processed by drying rather than by cooking, hence thename. Dry sausage is ordinarily served cold, without further cooking bythe housewife.

The manufacture of dry sausage customarily involves mixing desiredproportions of fat and lean means,'beef or pork, with selected spices,seasonings and curing materials to form an emulsion which is initiallycured at a few degrees above freezing (36 to 38 F.), for two or threedays depending upon the size of the meat particles so that they will bepreserved sufficiently to be smoked and dried.

The chill cured meat emulsion is then firmly packed into casings ofsuitable size and shape, and the ends of the casing are tied ready fordelivery to the drying room or Smokehouse,v

dependent upon the type of sausage. The smoked dry sausage is smoked andthen dried, while unsmoked dry sausage is dried only. The drying orcuring time will vary with the particular type of sausage beingprocessed and to some extent with the processing conditions. However, 60to 90 days is usually considered a minimum time and periodsof 120 to 180days or more are used under some circumstances.

The prrocessing of dry sausage is described fully in Sausage andReady-to-Serve Meats, published by the American Meat Institute. The termdry sausage" as used herein includes the entire range of dry and semidrysausages. The semidry sausages include the thuringer cervelates whichare dried for about days (other semidry sausages may be dried as short atime as 2 to 6 days). Dry sausage is usually sold in three differentforms; first, new sausage or semidry sausage, about 10 to 25 days aftersmoking (having about percent shrinkage); second, medium dry sausage,about 30 to 60 days after smoking (having about 32 percent shrinkage);and dry sausage, about 60 to 90 days or more after smoking (having about40 percent shrinkage).

Previously, the sausage meat emulsions were stuffed into casings formedof natural materials or animal products such as sewn beef middles andhog casings. More recently, considerable interest has been developed inutilizing certain synthetic materials out of which casings could beformed. Particularly, the industry has turned to the use of casingsformed of regenerated cellulose per se or of the product known in theart as fibrous casing and which is composed of cellulosic fibersimpregnated and held together by regenerated cellulose.

The use of such synthetic materials is not only desirable because of thegreater control over the supply that can be exercised in keeping withthe rapid growth and demand of the various packaged and/or cased meatproducts, but also the materials can be conventionally synchronized andextruded into seamless tubular form of preselected diameter. Mostimportantly, casings formed of the aforesaid fibrous materials, unlikethe natural product can be made sufficiently flexible as well as durableto be advantageously used in the stuffing step, while also beingsufficiently nonelastic that they will not stretch out of shape duringor subsequent to stuffing, but will retain a more constant shape andsize corresponding to that to which it was initially fabricated.

This, of course, permits a definite relation to be established betweenthe number of slices of the sausage and weight which may be assembled asa unit, and is obviously a highly desirable characteristic in themechanical high-speed packaging methods employed today. In addition, thecellulosic casings which there is a tendency for mold and/or so called"brown ring" to develop. This trouble is not encountered where naturalcasings are used since natural casings tend to expand and contract withthe sausage during curing.

2. Description of the Prior Art The coating or impregnation ofcellulosic casings to improve the adhesion of the casing to dry sausagesis well known in the prior art.

Voss et al. U.S. Pat. No. 1,978,744 discloses a cellulosic casing havingan internal coating of gelatin to improve adhesion toward dry sausages.Bose] U.S. Pat. No. 2,802,745 discloses a casing formed of regeneratedcellulose in which gelatin particles of a size less than 0.1 mm. weredispersed in the viscose from which the casing was formed so that thecasing has gelatin particles dispersed throughout the wall thereof.

Firth U.S. Pat. No. 3,158,488 discloses the use of monoglycerides oracetylated monoglycerides, either along or in combination with gelatin,as internal coatings for casings to be used for the processing of drysausages. Rose et al. U.S. Pat. No. 3,360,383 disclose the internalcoating of a cellulosic casing with a mixture of a protein, such asgelatin, and liquid smoke. The protein is hardened by the liquid smokeduring the drying process. Rose U.S. Pat. No. 3,367,786 discloses thecoating of a cellulosic casing internally with a coating mixture of asoluble protein, such as gelatin, and piperazine as a hardening agentfor the protein. Shiner et al. U.S. Pat. No. 3,378,379 discloses afibrous cellulosic casing coated internally with a water solublecationic thermosetting resin which is subsequently cured. Rose U.S. Pat.No. 3,383,223 disclose the internal coating of a fibrous cellulosiccasing with a mixture of a soluble protein and glutaraldehyde.

The prior art is generally subject to the objection that the variouscoating processes involve the use of an internal coating slug which isintroduced into the casing after formation of the casing prior todrying. This coating technique is expensive and uncertain in operationsince the depletion of the slug or coating solutions often results inerratic nonuniform coating.

SUMMARY OF THE INVENTION In recent years, regenerated cellulose casings,primarily of the fibrous paper-reinforced-type, have been made and soldcommercially for use inthe manufacture of dry sausages. These casingshave generally been coated on their inner surfaces with a thin layer ofgelatin or other materials which is effective in causing the casing toadhere to a dry sausage emulsion and follow the shrinkage of the casingduring curing. Gelatin coated casings of this type, however, are subjectto the disadvantage that they must be soaked in water prior to use andthis soaking generally results in a very substantial loss of the gelatincoating. As a result, there has been a substantial failure of adhesionof casings to dry sausages during processing which has resulted in theproduction of unsatisfactory sausage products. The loss of gelatinduring the soaking step can be offset by some extent by application of aheavier gelatin coating. The thickness of the gelatine coating howeveris determined largely by the concentration of gelatin in the solutionused to coat the casing and the coatings which have been usedcommercially are at a maximum practical thickness. Certain of the priorart patents, mentioned above, are concerned with the treatment ofgelatin coating solutions with various hardening agents, e.g.,glutaraldehyde, liquid smoke, piperazine, etc., which insure that thecoating provided on the inner surface of the casing is sufficientlyinsoluble to prevent leaching out during the presoak operation whileallowing the coating sufficient adhesion toward the dry sausage toperform its desired function of causing the casing to shrink with thesausage during processing. A further problem in the preparation of drysausage casings is the manner of application of the adhesive coating tothe inner surface of the casing. The most common and most economicalmode of application of the internal adherent coating has been the slugcoating technique. A solution of the coating material is introduced intothe casing in the form of a liquid slug. The opening in the casing isclosed and the casing moves past the sluginto the casing dryer. Theinternal surface of the casing is continuously coated and dried alongwith the casing in the dryer. This procedure has had the disadvantagethat the depletion rate of the coating solution is uncertain and erraticcoverage of the internal coating may result.

This invention is based on our discovery that fibrous reinforced casingsuitable for use in the preparation of dry sausages may be prepared byimpregnating a fibrous reinforcing paper, preferably a long fiberhemp-saturating tissue, with an aqueous solution or dispersion of awater-soluble or waterdispersible swollen protein. The protein used-maybe any of the soluble or dispersible proteins having molecular weightsabove 10,000 and an isoelectric point in the range from about pH 2 to pH6. These soluble proteins include (but are not limited to) the albumins,globulins, glutenins, prolamines, prolines, hydroxy prolines, histones,elastins, and protamines. Typical examples are egg albumin, edestin,glutenin, procollagen, gelatin, gliadin, etc. The solution isimpregnated in or coated upon the saturating tissue. In the case of themore soluble proteins solution is dispersed relatively uniformly throughthe saturating tissue, although there tends to be a higher concentrationon the surface at which the coating solution is applied. In the case ofthe water-dispersible proteins the coating forms primarily on thesurface of the saturating tissue. The coated or impregnated saturatingtissue is hardened or cross linked with a suitable cross-linking agentwhich is nontoxic under conditions of ultimate use. The cross-linkingagent used must either be nontoxic per se or must be chemically combinedin a form which is totally nontoxic in the finished product. Suitablecross-linking agents include formaldehyde (used at very low levels),glutaraldehyde, liquid smoke, etc. The hardening or cross-linking agentis preferably added in admixture with the solution or dispersion or theprotein under conditions of temperature insufficient to effect the crosslinking. During the drying operation the coating is heated to a highenough temperature to effect the desired hardening of cross linking.

The coated or impregnated paper is used in the formation of a fibrouscasing by forming a continuous elongated tube and saturating the tubeexternally with a solution of the desired casing forming material, whichis subsequently hardening or regenerated. Typically, the tubular casingwould be impregnated with viscose which would be subsequently coagulatedand regenerated to form a regenerated cellulose paperreinforced casing.Alternatively, the tubular casing paper could be impregnated withcollagen, polyvinyl alcohol, amylose, alginates, dextran, etc., to forma suitable reinforced casing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic viewillustrating the formation of fibrous casing in accordance with a moreor less standard commercial procedure.

FIG. 2 is a detail cross section of a portion of uncoated fibrous casingshowing the relative position of the supporting fibrous paper and theregenerated cellulose thereon.

FIG. 3 is a sectional view of a portion of fibrous casing as shown inFIG. 2 but provided with a hardened protein coating as taught be theprior art.

FIG. 4 is a diagrammatic view of the impregnation or coating of fibrouspaper with a protein solution or dispersion in accordance with apreliminary step in this invention.

FIG. 5 is a view in cross section of the wall of a fibrous casing havingprotein hardened and incorporated therein in accordance with thisinvention.

PRIOR ART PREPARATION OF FIBROUS CASING Referring to the drawing, thereis shown a somewhat diagrammatic view of the process and apparatus usedin the preparation of fibrous casing in accordance with the prior art.

In the drawing, a ribbon of paper 11, which is formed of naturalcellulosic fibers, and which is preferably a long fiber, hemp paperweighting 10-20 pounds per ream, passes from roll 12 over rollers 13 and14 and around guides 15 and 16 which form the paper into tubular form.

The paper then proceeds downwardly over mandrel 17 which may be a steelpipe having an outside diameter of two to seven inches, more or less,depending upon the size of the tube or casing which is to be produced.The mandrel 17 may be of a suitable length, conveniently 7 about 30 feetlong, and, as shown, can be suspended from a suitable support such as'an I- beam 18 or the like. The paper ribbon 11, now shaped in the formof a tube, passes downwardly over the mandrel 17, through a forming ring19 which is a metallic ring having an in: side diameter slightly largerthan the diameter of the paper tube passing through it. The forming ring19 functions to maintain the paper in the form of a tube until itreaches the coating die 21.

Coating die 21 is a hollow annular structure of metal or the like andcontains an annular opening 22, circumferentially of its inner face,through which viscose is applied to the outer surface of the downwardlypaper tube. Viscose is supplied under positive pressure from the chamberof die 21 through the annular slit 22 to thoroughly impregnate and coatthe paper tube which is moving downwardly through the die.

The sleeve 33, formed of metal or the like, which is shrunk onto themandrel 17, functions to effect more uniform application or viscosethrough the orifice 22 as the paper tube 11 passes downwardly thereover.A number of slip rings 220 are positioned on mandrel 17- at preselectedintervals. The slip rings 22a are preferably shrunk onto the mandrel atabout 3- foot intervals and function to keep the inside wall of theviscose-impregnated, paper tube from scraping against the outside wallof mandrel 17 as the tube moves downwardly.

Continuing in its downward movement, the viscose-impregnated, paper tube11 enters coagulating bath 23 contained in vessel 24. Coagulating bath23 contains about 5 percent sulfuric acid and various salts. On contactwith the acid bath, the viscose impregnated in and coated upon papertube 11 is coagulated and regenerated. The conversion of viscose toregenerated cellulose begins and continues within the bath as the tubemoves around roller 25 and continues as the tube moves over and underwiper rods 26 and 27, rollers 28, and then through washing baths anddrying tunnels not shown here, but being substantially the same as thoseused in the art of making regenerated cellulose casings, as exemplifiedin US. Pat. No. 1,937,225 and related patents. For convenience inunderstanding the overall intention, the steps of washing, drying andreeling and storage of the produce casing are shown diagrammaticallywithout reference to any particular apparatus for accomplishing thosesteps.

In carrying out the acid regeneration of cellulose in the paper tubing,acid for the bath 23 is supplied through pipe 29. The same kind andconcentration of acid is supplied to the interior of the casing throughthe mandrel 17 through a pipe 31. Spent acid from within the casing iswithdrawn through pipe 32 at a rate which is balanced by the incomingacid, as shown. In the preparation of casing in accordance with thisprocess, the speed of the casing in its downward movement isapproximately 2050 feet per minute, more or less, and the contact timein the acid bath 23 is of the order of 10-40 seconds.

The fibrous casing which is produced in this process is a tough, strongcasing useful in the preparation of large sausages such as bolognas andthe like. The same general process and apparatus is used in theproduction of other types of fibrous casing. For example, other solubleimpregnating materials, such as alginates, dextran derivatives, amylose,polyvinyl alcohol, collagen, etc., may be substituted for viscose toproduce a fibrous casing made from the hardened or regenerated materialderived from the coating or impregnating solution.

A cross section of a portion of the wall of a cellulosic fibrous casingis shown in FIG. 2. The reinforcing paper is thoroughly saturated andcoated with viscose during the process of manufacture and cellulose isregenerated therefrom. The cross section shown in FIG. 2 shows thereinforcing paper and regenerated cellulose impregnated therein and theregenerated cellulose coating as distinct layers. This structure of thefibrous casing is clearly shown when the casing is sectioned and stainedand observed under a microscope.

In the manufacture of fibrous dry sausage casings in accordance with theprior art, a fibrous casing prepared as described above is coatedinternally with a proteinaceous or other adherent coating which ishardened thereon as a distinct layer provided an adhesive bond betweenthe casing and the dry sausage processed therein. The cross section of aprior art fibrous day sausage casing is shown in FIG. 3. In this crosssection it is seen that the paper and impregnated regenerated celluloseand cellulose coating appear as distinct layers, as shown in FIG. 2,while the adherent hardened protein coating appears as a distinct layeron the paper portion of the casing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS in Fig. 4 there is shown adiagrammatic view of the process of coating fibrous paper in preparationfor the formation of dry sausage casing in accordance with thisinvention. A roll of fibrous paper (preferably a long fiberhemp-saturating paper) is unwound with the paper web 51 passing betweena coating roller 52 and press roller 53. Rollers 52 and 53 arepositioned in a coating tank 54 containing a solution 55 of protein suchas gelatin or the like. Alternatively, the coating bath 55 may be adispersion of a water dispersible (but insoluble) protein such as adilute slurry of collagen. The coated or impregnated web of paper whichleaves the rolls 52 and 53 passes through dryer 56 where the coatingsolution is thotoughly dried. The coating solution in tank 54 includes achemical hardening or crosslinking agent which is relatively inactive atroom temperature but which is reacted with the protein when heated to ahigher temperature in the dryer to harden the protein coating. The driedcoated or impregnated paper web is then rewound on windup roll 57.

In carrying out this invention, the coated or impregnated paper fromroll 57 is passed through the apparatus as shown in FIG. 1 to form thepaper into a continuous tubular fibrous casing and impregnate or coatthe paper with viscose (or other casing forming solution), theimpregnated paper being passed through a coagulating and regeneratingbath as described in connection with FIG. 1.

A cross section of a portion of the wall of the casing thus prepared isshown in FIG. 5. The casing wall comprises a regenerated cellulose layer58 secured on an integral with a layer 59 comprising paper admixed withhardened protein and regenerated cellulose. This casing differs fromthat shown in FIG. 3 in that the hardened protein is not present as adistinct layer on the inner surface of the casing but rather isdispersed throughout the paper and the regenerated cellulose is admixedtherewith. The amount of protein added to the paper in the treating stepshown diagrammatically in FIG. 4 is in the range from about 0.1 to 6.0percent based on the dry weight of the paper. At protein addons lessthan 0.1 percent the resulting product is ineffective as a dry sausagecasing, i.e., it does not adhere to and follow the surface of the meatduring processing. At protein addons greater than 6.0 percent the paperis blinded and nonporous to the extent that the viscose will notpenetrate adequately to form a properly reinforced casing. At higherprotein content, the cellulose is coated on the outside of the paperrather than impregnated throughout the paper and is not given the addedstrength and resistance against stretch which is produced in a typicalfibrous casing where the viscose thoroughly impregnates the reinforcingpaper.

The following nonlimiting examples are illustrative of the scope of thisinvention.

EXAMPLE 1 A gelatin-coating solution was prepared by dissolving 2 poundsgelatin in 50 pounds water and heating to F. with stirring. To thismixture there was added 11 pounds glycerin with 30 minutes additionalstirring. The solution was diluted with 16.5 pounds additional water andcc. ofa 25 percent aqueous solution of glutaraldehyde added. Thesolution was further diluted to 1 percent gelatin content and thencooled in preparation for coating fibrous casing paper.

A l4-pound hemp fiber-saturating tissue was coated with the gelatincoating solution at 80 ft./min. using the apparatus described in FIG. 43above. The paper picked up about 200 percent wt. of the solution whichrepresented a 2 percent gelatin content on the finished dried paper.

Next, the gelatin impregnated paper was slit to size and used in thepreparation of fibrous casing. The gelatin-impregnated paper was passedthrough the casing manufacturing operation as shown in FIG. 1 and asdescribed above. The casing produced is substantially as shown in FIG. 5cross section.

' Portions of the casing prepared in accordance with this example wereused in the preparation and processing of a variety of dry and semidrysausages including hard salami, Genoa salami, and summer sausage. Thecasings were prepared with untreated controls and control casings havinggelatin coatings inside prepared by a liquid slug-coating technique asused in the prior art. The untreated control casings separated from thesausage during processing. The casings produced in accordance with thisexample and the casings provided with an internal gelatin coating astaught by the prior art adhered adequatelyto the dry sausagecompositions throughout their processing.

EXAMPLE 2 A gelatin-coating composition was prepared as described inExample 1 and diluted 50 percent with additional water. A 14- pound hemppaper was impregnated with the solution and dried as described inExample 1. The paper had a gelatin content of 1 percent wt.

The gelatin impregnated paper was formed into fibrous casing asdescribed in Example 1 and the casing used in the preparation of avariety of dry and semidry sausages. The casing performed well andadhered to dry sausage and semidry sausage throughout the processingthereof. There was no substantial loss of gelatin from the casing duringthe presoak operation prior to stuffing with the sausage paste oremulsion.

EXAMPLE 3 A coating solution was prepared as described in Example 1 anddiluted to 0.05 percent gelatin content. When this solution is used tocoat hemp-saturating tissue as described in Example 1 there is a 0.1percent addon of gelatin in the finished paper.

The gelatin-treated paper is used in the formation of fibrous casingwhich is subsequently used in the preparation of a variety of dry andsemidry sausages. The casing adheres well to dry and semidry sausagesduring all phases of the processing thereof. However, at this level ofgelatin addon there are a few cases of casing separation from thesausage. It would appear therefore that a 0.1 percent gelatin addonrepresents about the minimum gelatin content for a dry sausage casing.

EXAMPLE 4 A casing treating solution was prepared as described inExample l and diluted to a 2 percent gelatin content.

A long fiber hemp-saturating tissue was coated with this gelatinsolution as described in Example 1 with a percent solution pickup. Thepaper was dried and found to have a 3.6 percent gelatin addon.

The gelatin impregnated paper was used in the preparation of fibrouscasing as described in Example 1 and the casing used in the preparationof a variety of dry and semidry sausages. The casing adhered to thesausages with greater uniformity than casing coated internally withgelatin in accordance with prior art techniques. There was nosubstantial loss of gelatin from the casing during the presoak operationprior to stuffing with sausage paste or emulsion.

EXAMPLE A gelatin-coating solution was prepared as described in Examplel and sufficient gelatin added to produce a 4 percent wt. concentrationof gelatin. The coating solution is used to coat a long fiberhemp-saturating tissue as described in Example 1. There is about a 200percent liquid pickup. This produces a gelatin addon of about 8 percentwt. on the paper.

When this paper is used in the preparation of fibrous casing it is foundthat the viscose solution does not penetrate adequately. The highgelatin content almost totally blinds the saturating tissue so that theviscose only coats the exterior of the treated paper and is not able topenetrate the paper adequately. It is not possible to produce asatisfactory fibrous casing from paper having this high gelatin addon.When the gelatin addon is reduced to about 6 percent the paper is onlypartially blinded and viscose penetration is poor but adequate toproduce a fibrous casing giving moderately good performance.

EXAMPLE 6 A gelatin-treating solution is prepared as described inExample 4 containing 2 percent gelatin and substituting about 0.2percent formaldehyde, based on the weight of gelatin used, forglutaraldehyde as the hardening or cross-linking agent for the gelatin.Solution is used in impregnation of a long fiber hemp-saturated tissuewith about 18 percent liquid pickup. The treated casing, after drying,has about a 3.6 percent wt. gelatin addon.

When this casing paper is made into fibrous casing in ac cordance withthe process described in Example 1 and used in the processing of dry ofsemidry sausages the casings are found to function satisfactorily incomparison with commercial dry sausage casing prepared in accordancewith the prior art internal coating techniques.

EXAMPLE 7 The process of coating fibrous paper was repeated as describedin Example 6 with 1.0 percent wt. liquid smoke (Char-Sol), based on theweight of gelatin, substituted for formaldehyde as the hardening orcross-linking agent. The coating solution was used to coat a long fiberhemp-saturating tissue to a 3.6 percent wt. gelatin addon.

The coated paper is used to manufacture a fibrous casing which is inturn used in the processing of dry and semidry sausage casing withsatisfactory results, equivalent to those obtained in Examples 4 and 6.

EXAMPLE 8 A collagen-coated solution (or slurry) is prepared by dilutinga 4.2 percent collagen slurry, produced in accordance with Talty et al.US. Pat. No. 3,408,918, to a. content of 0.40 percent collagen. A longfiber hemp saturating tissue was passed through the coater, as shown inFIG. 4, to coat the collagen slurry onto the paper. The collagen slurryincluded about 0.05 percent wt. glutaraldehyde based on the weight ofcollagen. The hemp-saturating tissue was coated on one side rather thanbeing thoroughly impregnated as in the case of a gelatin solution. Thecollagen slurry is coated on the paper and only partially impregnatedinto the porous structure of the paper. There is approximately 200percent takeup of the slurry with the result that the paper has acollagen addon of about 0.8 percent wt.

The collagen-coated paper, after drying, was used in the preparation offibrous casing in accordance with the process described in connectionwith the apparatus shown schematically in FIG. 1. In preparing fibrouscasing from collagen coated paper it is necessary that the collagencoating be turned to the inside of the tube and the viscose added to theuntreated side of the paper.

The casing prepared in this manner, having a 0.8 percent wt. addon ofcollagen, based on the paper weight, was used in the processing of avariety of dry and semidry sausages and gave excellent results ascompared to prior art internally coated fibrous casing used commerciallyfor the preparation of dry and semidry sausages.

EXAMPLE 9 of dry sausages and semidry sausages with entirelysatisfactory results as compared to prior art and dry sausage casingshaving internal coatings of gelatin.

EXAMPLE 10 The process described in Example 4 is repeated with wheatgluten being substituted for gelatin as the protein coating orimpregnant for fibrous casing paper. A coating solution is preparedcontaining 2 percent wheat gluten in place of the 2 percent gelatinsolution used in Example 4. When a fibrous casing paper is coated withthe solution and dried (the gluten being hardened or cross linked byreaction with a glutaraldehyde) the paper is found to have a 3.6 percentwt. addon of gluten.

The gluten-impregnated casing paper is used in the preparation offibrous casing using the process as described in Example 14. The casingis used in the preparation and processing of dry sausages and semidrysausages with satisfactory results. The casing adheres to and follows orshrinks with the sausage during processing.

We claim:

1. A method of preparing tubular artificial casings for the processingof dry sausages which comprises,

a. impregnating or coating a saturating tissue paper with a solution ordispersion of a water-soluble or dispersible protein having a molecularweight greater than about 10,000 and an isoelectric point in the rangefrom pH 2 to pH 6,

b. drying the impregnated or coated paper and hardening the proteintherein,

c. forming the dried paper into a continuous tube,

d. impregnating and coating the outer surface of said tube with asolution of a film-forming material, and

e. setting said film forming material to produce a paperreinforcedtubular film having the inner surface thereof containing hardenedprotein uniformly dispersed therein.

2. A method of preparing tubular artificial casings according to claim 1in which said solution of film-fanning material is viscose which is setby acid regeneration.

3. A method of preparing tubular artificial casings according to claim 2in which a hardening agent is added to the paper to harden the proteintherein.

inner surface thereof with a chemically hardened protein having amolecular weight greater than about l0,000 and an isoelectric point inthe range of from pH 2 to pH 6 and impregnated thoroughly with afilm-forming material over the protein-impregnated fibers of the paperand coated on the outer surface of said tube with a coating ofsubstantial thickness of said film-forming material.

2. A method of preparing tubular artificial casings according to claim 1in which said solution of film-forming material is viscose which is setby acid regeneration.
 3. A method of preparing tubular artificialcasings according to claim 2 in which a hardening agent is added to thepaper to harden the protein therein.
 4. A method of preparing tubularartificial casings according to claim 2 in which a hardening agent isadded to the paper in admixture with the protein dispersion or solutionto harden the protein on the paper during drying.
 5. A method ofpreparing tubular artificial casings according to claim 2 in which theprotein is applied to the paper in a concentration of 0.1-6.0 percentwt. based on dry weight of the paper.
 6. A method of preparing tubularartificial casings according to claim 2 in which the protein is gelatin.7. A method of preparing tubular artificial casings according to claim 2in which the protein is collagen.
 8. A method of preparing tubularartificial casings according to claim 2 in which the protein is gluten.9. A tubular artificial food casing comprising a tube of a saturatingtissue paper impregnated or coated on at least the inner surface thereofwith a chemically hardened protein having a molecular weight greaterthan about 10,000 and an isoelectric point in the range of from pH 2 topH 6 and impregnated thoroughly with a film-forming material over theprotein-impregnated fibers of the paper and coated on the outer surfaceof said tube with a coating of substantial thickness of saidfilm-forming material.